From what we can tell, it appears to be a tablet that turns into a phone when you fold its left and right side. It's definitely far more elegant than any foldable phone we've seen so far, and it makes more sense than, say, Royole's foldable phone, as it has a more usable form factor both in its folded and unfolded state. It's also quite fast and responsive, with its UI conforming to the folded state in less than a second.

The video poses a lot of questions, though. Some imperfections on the screen are visible (check out the upper edges of the screen at approximately 1/4 and 3/4 of its width), and we're not sure how far back the edges fold and what the phone's back looks like when it's folded up (presumably it's quite unwieldy).

In any case, this (if genuine) is definitely the most interesting foldable phone/tablet we've seen. If Xiaomi is behind it and if it can turn it into a mass-market product, it might become a strong competitor to whatever Samsung, Huawei and others are cooking.